Method of and apparatus for forming graphite molds or other refractory articles



p 15, 1931- H. E. WHITE ET AL 1 METHOD OF AND APPARATUS FOR FORMINGGRAPHITE MQLDS OR OTHER REFRACTORY ARTICLES Filed March 12, 1929 m m"mam W3 m2 3% ea 4 6 my 0 Patented Sept. 15, 1931 UNITED STATES PATENTerrics HAROLD E. WHITE, OF BUTLER, AND JOHN HESS AND OSCAR E. NEUHAUSEN,OF

ZELIENOPLE, PENNSYLVANIA, ASSIGNORS TO LAVA CBUCIBLE COMEANY, OFPITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENNSYLVANIA METHOD OF ANDAPPARATUS EoR FORMING GRAPHITE Home on oTHER REFRACTORY ARTICLESApplication filed March 12, 1929. Serial No. 346,287.

Our invention relates to the method of and apparatus for forminggraphite molds or other refractory articles, and particularly to themanufacture of hollow cylindrical molds and having one end thereofclosed and the other end opened, and of considerable height or depth.

In the making of molds of the general type of the present invention. twomethods have heretofore been followed; first, by spinning on a rotatingjigger machine; and, second, by pressing sections and afterwards unitingthe sections. Under the first method stated, it has been impossible toform molds of considerable height, due to the inability to operate atool inside the mold throughout its height or length, and the secondmethod is obj ectionable in that it has been impossible to formsatisfactory sectional molds.

The prime object of our invention is to provide a new and improvedmethod of manufacture of molds of the character stated, in one piece andof uniform structure, and the provision of new and improved apparatus bywhich our method of making the molds or other hollow refractory articlesmay be prac ticed.

In the accompanying .drawings, which illustrate a new and improvedmold'forming apparatus by which our method of making hollow elongatedmolds may be carried out:

Fig. 1 is a vertical sectional View through an apparatus embodying ourinvention, showing a. portion of some of the parts in elevation, and therelative positions of the parts at the beginning of the method;

2, a view similar to Fig. 1, showing the parts in final position; and

Fig. 3, a sectional view on the line III- TH ofFig.2.

Referring to the drawings, we have shown our apparatus in connectionwith a pneumat ically operated jarring machine A,of the usual or anypreferred type; as shown, the jarring machine includes a table 2, apiston 3, and a cylinder 'e having a hardened strike ing or contactingsurface 5.

Our apparatus is designed to be mounted on the jarring table, and asillustrated com prises a forming mold 6 preferably includ elongatedcasing, said split rings 9 being provided with fastening bolts 10.

The forming mold is preferably provided with an inner cylindrical hollowmember or tube 11 formed of thin sheet copper or aluminum, said tubeconstituting a lining for the mold, and is designed to receive thearticle forming material, the inside diameter of said tube beingsubstantially the same as the outside diameter of the graphite mold orother hollow article to be formed.

12 designates a closure cap for the upper end of the forming mold. Thiscap is provided with a central opening 13, the walls of which constituteguide means for a cylindrical plunger hereinafter described. In additionto the central opening 13, the closure cap 12 is provided with aplurality of openings 14 designed to receive rods 14a carried by theplunger and hereinafterrmore fully described. 0 The forming mold ispositioned and maintained in position on thejarring table 2 by means ofa holding ring 15 and a series of bolts 16 projecting therethrough andhaving their screw threaded ends entered in threaded sockets in thetable. It is obvious, however, that the forming mold may be secured tothe table by any suitable means.

Mounted for operation within the forming mold, we provide a gravityoperable material piercing plunger 17 of cylindrical form and having acentral bore 18 extending throughout'the length of the plunger. Thisplunger 17 is preferably provided with a thin metallic covering or tubeindicated at 6, formed of thin sheet copper or aluminum.

The lower end of the plunger is closed bya plug 19 adapted to bethreaded thereto, as shown at 20.

Said plug 19 is provided with an air passage 21adapted to be controlledby a springpressed valve 22. The opposite end of the hollow piercingplunger 17 is provided with .a cap 23 having a centrally disposedthreaded depending portion 24 adapted to be. entered within the hollowplunger and secured to the interiorly threaded portion thereof. Cap 28is formed with a central opening 26 communicating with the bore of theplunger, and is further provided with openings 27 adapted to receiverods 14a passed therethrough and designed to be passed through theclosure cap 12 of the forming mold, for the purpose of engaging agravity operable weighted follower 29 associated with the hollow plungerand arranged Within the forming mold.

It will be noted that the outside diameter of the piercing plunger 17 isconsiderably less than the inside diameter of'the'forming mold or thelining thereof, and that the fol lower 29 is of such diameter as to havea sliding contact with the interior of the tubular lining 11. Thefollower 29 is formed with threaded sockets 30 adapted to receive the lthreaded ends of the rods 14a when the follower and the head or cap 23of the plunger are in the position shown by Fig. 2. By means of thisconstruction, itwill be noted that the heads or caps 12 and 23 of theforming mold and the plunger, together with the follower, may be raisedfree of the forming mold after the completion of the mold being formed.

In the manufacture of graphite molds under our process, the mold formingmaterial is deposited in the forming mold, filling the lower portionthereof and extending, for instance, up to the line hh of Fig. 1. Inmaking these molds, a mixture consisting of substantially percentnatural graphite, 35 percent refractory clay, and 15 percent siliconcarbide fines may be employed. Water is added to this material, and itis mixed until the desired plasticity is obtained. After proper agingand remixing, a suitable quantity of mixture in an unconsolidated stateis then introduced to the molding apparatus, as stated above. After theintro duction of this mixture, the plunger and the associated followerare positioned within the forming mold and assume the position shown byFig. 1.

Ourmethod contemplates forming the unconsolidated plastic material ormixture into a thoroughly compacted homogeneous mass of the desiredconfiguration, by the combined action of jarring and displacement of thematerial while subjected to pressure, and our method may beadvantageously followed by the employment of the apparatus iereinaoovedescribed.

The parts of the apparatus being in the position shown by Fig. 1. withthe desired measured quantity of material P deposited 3 in the formingmold, the jarring machine is started and the heavy gravity-operatedplunger will gradually descend into the material, forcingit upward intothe space between the outer surface of the plunger and the inner surfaceof the forming mold or its tubular lining. The upward flow 0f thematerial is against the downward pressure exerted by the followerresting on the upper surface of the material or mixture. Continuing theoperation, the follower is raised into the position near the top of the.forming mold as shown by Fig. 2. Any surplus of mixture may bedischarged through a take-out opening shown at (Z. This opening may alsobe employed to permit the escape of air at the start of the operation.

After a mold is formed in the manner described and when the follower isin the position shown by Fig. 2, the rods 14a may be inserted to engagethe follower, whereby the plunger and the follower may be lifted free ofthe forming mold as a unit, thus releasing the pressure on the finishedarticle without rupturing. As the plunger is withdrawn, apartial vacuummay be created within the cavity of the hollow article being formed, andin order to relieve this, we have provided the spring-pressed valve 22operable to admit air.

After the removal of the plunger, etc, as above described. the outercasing of the forming mold is separated from its tubular lining byloosening the encircling clamps, after which the tube with the containedgreen mold are placed on a drying floor. When sufficiently dry, thealuminum or copper tube or casing is removed from the formed article andmay be re-used.

For the purpose of guiding and maintaining the plunger 17 in the desiredoperative position, we have provided a tubular member 31 having an endscrew-threaded and entered in and secured to the threaded wall of openin13 of the cap 12.

We claim:

1. The method of making a hollow refractory article which consists inplacing an unconsolidated mixturein a container, jarring the mixture anddisplacing the mixture by the piercing action of a forming tool to causea flow thereof upwardly in the container while pressure is applied tothe upper surface of the upwardly flowing mixture exterior of theforming tool.

2. The method of making a hollow refractorv article which consists inplacing an unconsolidated plastic mixture in a container. simultaneouslyiarring and piercing the mixture in the container while pressure isapplied to the upper surface of the mixture characterized in that themixture is caused to flow upwardly within the container by agravity-operated piercing tool and that pressure is applied to the uppersurface of the flowing mixture exterior of the piercing tool.

3. The method of making a hollow refractorv article which consists inplacing an unconsolidated plastic mixture in a container, simultaneouslyjarring and flowing the mixture-in the container while pressure isapplied to the upper surface of the mixture characterized in that themixture. is caused to flow upwardly within the container by a gravityoperated piercing tool and that pressure is applied tothe upper surfaceof the flowing mixture exterior of the piercing tool by agravity-operated member, and that the material is subjected tosubstantially the same pressure during the piercing action by thepiercing tool and said member.

4. In apparatus for forming hollow refractory articles, a forming moldintowhich the article-forming material is deposited, a gravity operableplunger movable within the mold to displace and compress the containedmaterial, and a gravity operable follower associated with the plungerand disposed within the forming mold.

5. In apparatus for forming hollow refractory articles, a forming moldinto which the article-forming material is deposited, a grav ityoperable plunger movable within the mold to pierce and compress thecontained material, and a gravity operable follower associated with theplunger and disposed within the forming mold, said plunger having anoutside diameter considerably less than the internal diameter of themold and said follower having 7 an outside diameter substantially equalto the internal diameter of the mold.

6. In apparatus for forming hollow refractory articles, a forming moldcomprising a cylindrical divided casing having a removable liner intowhich the article-forming material is deposited, a closure cap for saidmold having guiding means thereon, a gravity operable plunger movablewithin the mold and guided by the cap to pierce and compress thecontained material, and a gravity operable follower associated with theplunger and disposed within the liner.

7. In apparatus for forming hollow refractory articles, a forming moldinto which the article-forming material is deposited, means forpositioning the forming mold on a jarring table, a hollow cylindricalgravity operable. plunger movable within the mold to pierce and compressthe contained material, valve means carried at the lower end of thehollow plunger, and a gravity operable follower associated with theplunger and disposed within the forming mold.

In testimony whereof we afiix our signatures. V

HAROLD E. WHITE. JOHN HESS.

OSCAR E. NEUHAUSEN.

CERTIFICATE OF CORRECTION.

Patent No. 1,823,180. Granted September 15, 1931, to

HARGLD E. WHITE ET AL.

It is hereby certified that the name of the assignee in the abovenumbered patent should have been Written and printed as Lava CrucibleCompany of Pittshnrgh, of Pittsburgh, Pennsylvania, a corporation ofPennsylvania, instead of "Lava Crucible Company, of Pittsburgh,Pennsylvania, a corporation of Pennsylvania", as shown by the records ofassignments in this office; and that the said Letters Patent should beread with this correction therein that the same may eonform to therecord of the case in the Patent Office.

Signed and sealed this 3rd day of November, A. D. 1931.

M. J. Moore,

(Seal) Acting Commissioner of Patents.

